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/*
* linux/drivers/acorn/char/i2c.c
*
* Copyright (C) 2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* ARM IOC/IOMD i2c driver.
*
* On Acorn machines, the following i2c devices are on the bus:
* - PCF8583 real time clock & static RAM
*/
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/hardware/ioc.h>
#include <asm/system.h>
#define FORCE_ONES 0xdc
#define SCL 0x02
#define SDA 0x01
/*
* We must preserve all non-i2c output bits in IOC_CONTROL.
* Note also that we need to preserve the value of SCL and
* SDA outputs as well (which may be different from the
* values read back from IOC_CONTROL).
*/
static u_int force_ones;
static void ioc_setscl(void *data, int state)
{
u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
u_int ones = force_ones;
if (state)
ones |= SCL;
else
ones &= ~SCL;
force_ones = ones;
ioc_writeb(ioc_control | ones, IOC_CONTROL);
}
static void ioc_setsda(void *data, int state)
{
u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
u_int ones = force_ones;
if (state)
ones |= SDA;
else
ones &= ~SDA;
force_ones = ones;
ioc_writeb(ioc_control | ones, IOC_CONTROL);
}
static int ioc_getscl(void *data)
{
return (ioc_readb(IOC_CONTROL) & SCL) != 0;
}
static int ioc_getsda(void *data)
{
return (ioc_readb(IOC_CONTROL) & SDA) != 0;
}
static struct i2c_algo_bit_data ioc_data = {
.setsda = ioc_setsda,
.setscl = ioc_setscl,
.getsda = ioc_getsda,
.getscl = ioc_getscl,
.udelay = 80,
.timeout = 100
};
static struct i2c_adapter ioc_ops = {
.id = I2C_HW_B_IOC,
.algo_data = &ioc_data,
};
static int __init i2c_ioc_init(void)
{
force_ones = FORCE_ONES | SCL | SDA;
return i2c_bit_add_bus(&ioc_ops);
}
__initcall(i2c_ioc_init);
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